Device for forming a glue profile for cross-base sacks

ABSTRACT

An apparatus ( 30, 100, 200 ) is presented for forming a glue profile for gluing the bottom sheets ( 2 ) and/or folded bottoms ( 1 ) of tube portions which ( 1, 2 ) [sic] are used for forming block bottom bags ( 19 ).  
     The device ( 30,100,200 ) comprises the following features: 
         at least one first glue reservoir ( 101 ) or at least one glue input ( 111   a,b ) from which glue is supplied,    glue lines ( 110 ) which transport glue to the gluing locations,    a number of glue valves ( 32 ) which are to open and close individually, the glue profile ( 4 ) being definable based on the selective opening of the valves ( 32 );    glue outputs ( 71 ) which are allocated to the valves ( 32 );    at least one second glue reservoir ( 102 ), by means of which the second glue reservoir ( 102 ) can be pressurized.        

     Methods for forming a glue profile ( 4 ) are also laid out.

The invention relates to an apparatus for forming a glue profile forgluing the bottom sheets and/or folded bottoms of tube portions that areused for forming block-bottom bags.

In other technical fields, an apparatus for forming a glue profile forgluing bag components is already known. The bag components are then usedfor forming bags. DE 199 35 117 suggests one such apparatus for formingglue profiles of bags. It comprises the following features:

-   -   a plurality of glue valves which open and close individually,        the glue profile being definable through the selective opening        of the valves;    -   a glue line which is connected to the valves;    -   glue outputs which are allocated to the valves.

DE 199 35 117 describes a device in which the glue first reaches valvesvia a glue line and is then extruded onto a drum through the glueoutputs thereof. The drum transfers the glue onto the bag components.But neither DE 199 35 117 nor any other publication suggests formingblock-bottom bags with the aid of such an apparatus. In order tounderstand this fact, the knowledge of the manufacturing processes ofvarious bag types is important. In this regard, one should emphasize thedifferences between pinch bottom bags and block bottom bags. The formingof block bottom bags is laid out in De 090 145 48 U1 and De 3020043 A1for example. In the gluing of the bottom sheets and folded bottoms, verylarge amounts of glue that is difficult to convey must be distributedover a large format width.

Besides this, the application of the glue profile is usuallyintermittent; that is, specific regions are glued into the individualform of the desired bag components. Glue application does not occur inthe spaces between.

In the case of block bottom bags, either the folded bottom or the bottomsheets attached to them or both of the previously named elements to beglued are to be covered with a sheet of glue and in the end are broughttogether.

According to the prior art, the gluing of the components of the bagoccurs by means of a blank—often referred to as a stereotype—which isfastened to a rotating drum being brought into contact with glue drumsor other glue storage or transfer parts as the drum turns, and isthereby charged with glue. Later in the drum rotation, the format platetransfers the glue stored therein onto the bag component.

To that end, the blank is provided with characteristic elevations, whichare adjusted to a particular bag format. The blanks are swapped out ifbags with other dimensions are to be produced on the bottom layingapparatus.

The described method of glue application has proven useful in bottomlaying apparatuses for paper bags, because large amounts ofdifficult-to-handle starch glue can be applied cleanly that way.

However, the disadvantages of these device include the need to exchangeblanks with each format change. Glue formats of valve arrays—i.e.configurations of glue valves at a gluing station—can be extruded inorder to obviate the need for blanks. But first it is necessary toovercome the difficulties which glue application poses for the valves.

This object is achieved by an apparatus comprising the followingfeatures:

-   -   at least one first glue reservoir or at least one glue input        from which the glue is conducted;    -   glue lines which transport glue to the gluing locations;    -   a plurality of glue valves which open and close individually,        the glue profile being definable by the selective opening and        closing of the valves;    -   glue outputs which are allocated to the valves;    -   at least one second glue reservoir, which his charged with an        overpressure and connected to at least two valves;    -   a pressure reservoir by means of which the second glue reservoir        can be charged with pressure.

In an inventive apparatus, it is possible to conduct glue from a gluemixing apparatus or glue container to the gluing locations. At thegluing locations, a plurality of valves forms the glue profile, which iseither extruded onto the bag components directly after leaving the glueoutputs or transferred to a transfer element like a drum according to DE199 35 117 first and then transferred onto the bag components.

The setting of different glue profiles is achieved by the selectiveopening of the valves. The glue supply of at least two valves isachieved by means of a common glue reservoir in which glue is storedand/or through which the glue can be conducted. Besides saving expensiveglue line components, this measure ensures that the valves are chargedwith the same or similar pressure, and, as a result, identical orsimilar glue trails are extruded.

This glue reservoir corresponds with a pressure reservoir which cancompensate or at least cushion pressure fluctuations in the second gluereservoir, potentially in a fraction of a second.

There are many possibilities for realizing such a pressure reservoir. Anadvantageous embodiment of the invention provides a pressure reservoirwhich contains a compressible medium which is under pressure.

Another possibility is to provide at least a third glue reservoir inwhich the glue is under a higher pressure than in the second gluereservoir.

Further exemplifying embodiments of the invention emerge from thepresent description and claims.

The figures show:

FIG. 1 a glue application apparatus for bag bottom sheets according tothe prior art;

FIG. 2 a glue application apparatus for block bottom bags according tothe prior art;

FIG. 3 view of an inventive device;

FIG. 4 View of an inventive device which generates complex glue formats.

FIG. 5 a) A sheet 2 with a u-shaped glue format

FIG. 5 b) a sheet 2 with a glue format in the shape of a rectangularframe

FIG. 6 schematic structure of an inventive apparatus

FIG. 7 schematic structure of another inventive apparatus

The figures below represent inventive glue application apparatuses forblock bottom bags and apparatuses of the prior art. The inventiveapparatuses that are represented glue only bottom sheets 2. But theycould glue block bottoms 1 equally well.

FIG. 1 represents a glue application apparatus as it is typicallyemployed in the prior art for gluing bottom sheets 2. In this apparatus,glue is transferred from a glue cylinder 11 onto the blank or stereotype12, which is borne by a stereotype cylinder 13 and moved about the axisof the stereotype cylinder 13 in the direction of arrow 16. In thisrotating movement, the stereotype or blank 12 transfers glue onto thebottom sheets 2, which are borne by the clamping cylinder 14 during theglue transfer process. Before that, the bottom sheets 2 are conveyedalong the dotted line 18 in the direction of arrow x into the nipbetween the cylinders 13 and 14 by a transport device which is notrepresented. The rotation of the clamping cylinder 14 in the directionof arrow 15 conveys the glued sheets further to the bag bottoms 1, whichare transported in the direction of arrow w by a transport device thatis not represented. The bags 19 are terminated by the bag bottoms 1.Between the clamping cylinder 14 and the transport means for the bags, apressure is built, which presses sheets 2 and bag bottoms together,thereby joining them permanently.

FIG. 2 represents another glue application apparatus 20 according to theprior art which is typically employed for gluing bag bottoms 1. To thatend, a stereotype or blank 12, which is usually attached to theperiphery of the stereotype cylinder 13, is brought into contact withthe glue transfer cylinders 28 through the rotation of the stereotypecylinder 13 about its axis 25 in the direction of arrow 16, and is thuscharged with glue. To that end, the blank has depressions which are notrepresented, which are filled with glue during contact with the gluetransfer drums 28.

On their part, the glue transfer drums 28 limit the opening of a gluereservoir 21 and transport glue from the glue reservoir 21 to thestereotype 12 on their perimeter during rotation.

Further ahead in the course of rotation of cylinder 13, the stereotypeor blank 12 reaches the nip 24 between the cylinders 29 and 13. There,the stereotype 12 transfers glue onto a bag bottom 1. The bag waspreviously transported along the dotted line 26 into the nip by aconveyor device that is not represented.

Given a change of bag formats, the blanks 12 of the glue stations 10 and20 represented in the FIGS. 1 and 2 are replaced with blanks tailored tothe new bag format.

FIG. 3 represents a sketch of a sheet gluing station 30 of an inventiveblock bottom laying machine which provides sheets 2, already singled andbeing conveyed in the direction of arrow x, with glue trails 3. To thatend, the gluing station 30 is equipped with an application head 31. Thisapplication head is provided with glue by means of the tube 33. Insidethe application head 31, the glue is distributed by suitable glue linesto the valves 32, which are attached to the application head 31 in tworows that run transverse to the transport direction x of sheets 2. Thesevalves 32 are at least able to release or block the glue flow. They aredrivable by means of external, preferably electrical, signals, and they32 [sic] withstand the glue pressure.

Located on the bottom of the application head 31, which is notrepresented in FIG. 3, are glue outputs 71, through which the glueleaves the application head 31and forms the glue trails 3. Arrow xpoints in the transport direction of the sheets 2, whereas arrow ypoints in the horizontal direction running transverse thereto.

FIG. 4 represents a gluing station 30 which is apparently constructedexactly like the gluing station from FIG. 3. The different glue trails44 to 47 show how the different glue formats can be realized with such adevice, without the blanks having to be used. A variation of thestereotype width, i.e. the expanding of the glue area in direction y,can be realized by switching valves 32 on or off during the productionof bags of this glue format. When so switched off, the valves areinactive for the entire duration of the gluing of sheets 2 or bagbottoms of a format. That way, rectangular glue formats as representedin FIG. 3 emerge, which are formed from continuous glue trails 3, 47that are usually the same length.

But to accomplish this, the valves, which are active during theproduction of a glue format, must be closed after the production of acontinuous glue trail 47 and re-opened with the arrival of the next asyet unglued sheet 48 at the glue outputs. Already this work sequence, atnormal gluing rates, leads to substantial demands on the switching timeof the valves 32. If further variations of the form of the glue formator the glue quantity are performed, the valves 32 must be able to beopened or closed even faster than in the production of continuous gluetrails 47.

A substantial variation of the amount of glue applied is possibleparticularly by applying multiple interrupted glue trails 44. Thefurther variation of the form of the glue format—including substantialdeviations from a rectangular shape—requires the application of short 45and interrupted glue trails 46. Frequently, the glue formats 4 arerequired to take the shape of a u 4 a) or a rectangular frame 4 b), asrepresented in FIGS. 5 a) and b). To that end, the valves must be drivendifferently during the gluing of a bag component 1, 2.

It is advantageous when the valves 32 that are provided in the bottomlaying machine have a switching time—that is to say, are switched in atime-span—which is shorter than 5 ms. A majority of the variations ofglue formats needed in the industry that can be performed by modifyingthe individual glue trail lengths in direction x can then be realized atfast gluing rates in the manner described above.

The different glue trails 45 to 48 give some idea of how flexibly suchan inventive apparatus can generate formats when the valves are switchedeven faster.

The embodiments of the invention represented in FIGS. 3 and 4 are justas suited to the actual gluing of sheets that have already been singledas they are to the gluing of paper webs which can be singled later. Thegluing can be performed analogously on bag bottoms as well.

In the exemplifying embodiment represented in FIGS. 3 and 4, the secondpressure reservoir 102 comprises the glue lines in the interior of theapplication head 31, which are not represented in FIGS. 3 and 4, as wellas the tube 33. It terminates at the pressure regulator 105. It isadvantageous when this pressure regulator or another valve that connectsthe second glue reservoir with a pressure reservoir also has an openingand closing time of shorter than 5 ms. If the pressure regulator isconfigured as a passive element, it must be able to respond within 5 ms.

As already mentioned, FIGS. 5 a) and b) represent a u-shaped 4 a) and arectangular glue format 4 b) on two sheets 2. The u-shaped glue formatis composed of continuous 3 and short glue trails 45 [sic]. The glueformat in the shape of a rectangular frame 4 b) is composed ofcontinuous 3 and interrupted glue trails 46. The different course of theglue trails is the result of a selective driving of the glue valves 32during the gluing of a bag component 1, 2.

All exemplifying embodiments of the invention described in the subclaimsand represented in the figures are suitable for direct as well asindirect gluing of bag components 1, 2 in which the glue is firsttransferred to a drum or other form before reaching the bag components.

FIG. 6 is a schematic representation of a complex inventive apparatus100. The first glue reservoir 101 comprises the glue input funnel 111 avia which glue is fed to the apparatus, the glue line 111 b, the gluetank 111 c, and the parts of the glue line 110 located upstream from thepump 106 in the direction of glue transport.

The pump 106 presses the glue into the third glue reservoir 103, whichcomprises the part of the glue line 110 following the pump 106, the gluetank 113, and the part of the glue line 110 between the glue tank 113and the pressure regulator 105. The third glue reservoir 103 is under ahigher pressure than the second 102. It thus serves as a pressurereservoir with respect to the second glue reservoir 102.

The pressure regulator 105 forwards glue from the third glue reservoirto the second. It can reduce the pressure to the pressure prevailing inthe second glue reservoir 102. Like the two other glue reservoirs, thesecond glue reservoir 102 also comprises all parts of glue lines 110,114, 115, 116, 117, 118, which are positioned upstream from therespective blocking valves and are therefore under the same pressure asglue tank 112.

In the operation of the inventive apparatus 100, the glue flows throughthe glue tank 112 —which can have a very small volume in the presentembodiment of the invention—and reaches the valves 32. These are openedor closed according to the glue format to be formed and pass the glue tothe upper glue channels 72. A part of these upper glue channels 72branches again in the application head 31 into the lower glue channels73, which opens into the glue outputs 71. In the gluing process, theglue exits the application head 31 via these glue outputs and is eitherdirectly or indirectly transferred to the bag components 1, 2.

The second glue reservoir 102 can be emptied another way, however. Gluecan be let into the glue discharge container 131 via the glue dischargeline 116 and the outlet valve 122. That way, a faster glue exchangeand/or a fast depressurization can be performed. Cleaning media such aswater or compressed air can be conducted over the cleaning medium line118 for cleaning purposes. In particular, if liquid cleaning media areused, the utilization of collecting containers 130 for these media isrecommended. The cleaning medium discharge 119 and the outlet valve 121can be attached directly to the second glue reservoir.

A regular glue circulation between the first 101 and second gluereservoir 102 can be made possible by a glue drain 114. Here, the gluecan advantageously pass through a pressure reducer/valve 123.

There remains the pressure measuring devices 132, 133, which permit themeasuring of the pressure directly at the second and third gluereservoir. These pressure meters can be necessary for the purpose ofmonitoring the correct gluing. Allow even a real controlling of theamount of glue applied and other process parameters [sic].

FIG. 7 represents another embodiment of the invention 200. Thisembodiment also comprises the three glue reservoirs 101, 102, 103,whereby the third glue reservoir 103 simultaneously serves as pressurereservoir for the second glue reservoir. Unlike the embodimentrepresented in FIG. 6, the second and third glue reservoirs 102, 103break down into subreservoirs 102 a-dand 103 a,b. The subreservoirs 102a-d are equipped with gas cushions, which are not represented but whichare located inside the glue tanks 112 a-d. These gas cushions serve asadditional pressure reservoirs for the second glue reservoirs 102 a-d.Another difference compared to exemplifying embodiment 100 consists inthe glue lines 117, which—as already described in connection with FIGS.3 and 4—extend inside the application head 31. In such an exemplifyingembodiment, a majority or even the whole volume of the second gluereservoir 102 can be made available by such glue lines 117 and/or gluetubes 33.

Furthermore, it is advantageous when the glue is conducted over anuninterrupted glue line 101, 102, 103, 105, 106, 110 from a gluekitchen, in which starch glue is mixed together from its components andconditioned by stirring or rotating, to the second glue reservoir. Inthat case, the central glue kitchen of a bag production plant is thefunctional equivalent of a first part of the first glue reservoir 101.But is also possible to provide decentralized glue preparation stations,each of which is allocated to a respective inventive apparatus.

Reference Characters

-   x sheet transport direction-   y direction transverse to sheet transport (horizontal)-   z direction transverse to sheet transport (vertical)-   w direction of transport of bag bottoms 1-   1 bag bottom-   2 sheet-   3 glue trail-   4 rectangular glue format-   4 a) u-shaped glue format-   4 b) glue format in the shape of a rectangular frame-   10 known gluing station, preferably for sheets-   11 glue cylinder-   12 stereotype or blank-   13 stereotype cylinder-   14 clamping cylinder-   15 arrow in direction of rotation of clamping cylinder 14-   16 arrow in direction of rotation of stereotype cylinder 13-   17 arrow in direction of rotation of glue cylinder 17-   18 dotted line-   19 bag-   21 glue reservoir-   24 nip-   25 axis of cylinders-   26 dotted line sketched in the transport path of the bags-   27 direction of cylinder rotation-   28 glue transfer cylinder-   29 impression cylinder-   30 inventive gluing station-   31 application head or plate-   32 valves-   32 nvalve of the nth valve row-   33 glue line/tube-   44 interrupted glue trail at regular intervals-   45 short glue trail-   46 interrupted glue trail-   47 continuous glue trail-   48 unglued sheet-   71 glue output-   72 upper glue channel-   73 lower glue channel-   100 first inventive apparatus-   101 1^(st) glue reservoir-   102 2^(nd) glue reservoir-   102 a-d 2^(nd) lower reservoir-   103 3^(rd) glue reservoir-   103 a-d 3^(rd) lower reservoir-   105 pressure regulator-   106 pump-   110 glue lines-   111 a glue input funnel-   111 b glue line-   111 c 1^(st) glue tank-   112 2^(nd) glue tank-   112 a-d glue tanks of the lower reservoirs 102 a-d-   113 3^(rd) glue tank-   114 glue drain-   115 input valve for cleaning media-   116 glue discharge/depressurization-   117 glue supply in the head-   118 cleaning medium supply-   119 cleaning medium discharge-   121 discharge valve/cleaning medium-   122 discharge valve for glue and depressurization-   123 pressure reducer/valve at glue discharge 114-   124 response valve for cleaning medium-   130 discharge container for cleaning media-   131 glue discharge container-   132 pressure meter at 2^(nd) reservoir-   133 pressure meter at 3^(rd) reservoir-   200 second inventive apparatus

1: Apparatus (30, 100, 200) for forming a glue profile for gluing thebottom sheets (2) and/or folded bottoms (1) of tube portions which (1,2) [sic] are used for forming block bottom bags (19), whereby the device(30,100,200) comprises the following features: at least one first gluereservoir (101) or at least one glue input (111 a,b) from which glue issupplied, glue lines (110) which transport glue to the gluing locations,a number of glue valves (32) which are to open and close individually,the glue profile (4) being definable based on the selective opening ofthe valves (32); glue outputs (71) which are allocated to the valves(32); at least one second glue reservoir (102), which communicates withat least two valves (32); a pressure reservoir (103) by means of whichthe second glue reservoir (102) can be pressurized. 2: Apparatusaccording to claim 2, characterized in that the pressure reservoir (103)comprises a compressible medium—preferably a gas such as air—which isunder pressure. 3: Apparatus according to claim 1 or 2, characterized inthat the pressure reservoir (103) comprises at least a third gluereservoir (103), in which the glue is under a higher pressure than inthe second reservoir (102). 4: Apparatus according to claim 3,characterized in that at least one third glue reservoir (103) isdisposed between the first (101) and second (102) glue reservoir in thedirection of glue transport. 5: Apparatus according to claim 4,characterized in that the at least one second glue reservoir and the atleast one third glue reservoir are connected to one another by means ofa pressure regulator (105). 6: Apparatus according to claim 5,characterized by a pressure regulator (105) which comprises a valve withwhich the connection between the second and third glue reservoirs can beopened and closed, whereby the opening time and closing time of thevalve are each shorter than 5 ms. 7: Apparatus according to claim 4,characterized in that at least one pump (106) is provided between thefirst (101) and third glue reservoir (103), which pressures the glueinto the third glue reservoir (103). 8: Apparatus according to claim 4,characterized in that the third glue reservoir (103) also communicateswith a pressure reservoir. 9: Apparatus according to claim 3,characterized in that the at least one third glue reservoir comprisesseveral glue pressure levels connected in series. 10: Apparatusaccording to claim 1, characterized by at least one depressurizationvalve (122), which is in direct contact with the second glue reservoir(102) and with which the pressure in the at least one second gluereservoir (102) can be reduced. 11: Apparatus according to claim 10,characterized in that the at least one second glue reservoir can bedepressurized to atmospheric pressure by means of the at least onedepressurization valve (122). 12: Apparatus according to claim 1,characterized in that besides the glue supply system (101, 102, 103,105, 106, 110) which conducts glue in the direction of the valves (43),a glue discharge system (114) is also provided, which allows thedischarge of glue by the valves (32) without the glue passing throughthe valves (32). 13: Apparatus according to claim 12, characterized inthat a glue circulation and/or glue exchange in the apparatus (100, 200)can be performed by the interaction of the glue supply system (101, 102,103, 105, 106, 110) and the glue discharge system (114). 14: Apparatusaccording to claim 3, characterized in that a pressure meter (132, 133)is provided at least at one of the following locations: at the secondglue reservoir (102), at the third glue reservoir (103). 15: Apparatusaccording to claim 2, characterized in that the at least one second gluereservoir is provided with an additional supply and/or drain (119)through which a cleaning medium like water or compressed air can beconducted. 16: Apparatus according to claim 8, characterized in thatglue (131) and/or water vessels (130) are provided, in which exchangedglue or used water which is discharged from the glue supply system canbe collected. 17: Apparatus according to claim 1, characterized in thatthe at least one first glue reservoir (101) or the at least one glueinput (111 a,b) from which glue is supplied comprises a glue agitator inwhich components of starch glue—such as starch and water—can be placedand stirred into starch glue. 18: Method for forming a glue profile forgluing the bottom sheets (2) and/or folded bottoms (1) of tube portionswhich (1,2) are used for forming block bottom bags (19), comprising thefollowing features: glue is supplied to a glue transport system (101,102, 103, 110, 111) via at least one first glue reservoir (101) or atleast one glue input (111 a,b), glue is transported in the [sic](101,102,103,110,111) to the gluing locations by glue lines (110),valves (32) are driven which extrude the glue onto the bag components(1,2) through assigned glue outputs (71), whereby the driving isselective, so that a glue profile (4) is defined, whereby the glue, inpassing through the glue transport system, first passes a third gluereservoir (103) and then a second (102), whereby the second gluereservoir (102) communicates with at least two valves (32), whereby thepressure in the third glue reservoir (103) is higher than in the second(102). 19: Method according to claim 18, characterized in that the atleast one valve (105) that connects the second glue reservoir (102) withthe third glue reservoir is opened and closed with the same frequencywith which the bag components pass the gluing station (30, 100, 200).